Using the experiments simulated the circumstance of pH and anaerobe in stomach and tharm of human in vitro,it is studied that the influences of absorption capacity for cholesterol and sodium cholate and promotion for proliferation of Bifidobacterium longum on soluble dietary fiber (SDF).Otherwise,the composition of SDF was determined.The SDF is prepared from peach pomace with two ways,one is water-extracted and another is that the remains of water-extracted are treated by the enzyme solution.